Re: Can I overload with unused arguments to make the code clear?

From:
=?ISO-8859-1?Q?=D6=F6_Tiib?= <ootiib@hot.ee>
Newsgroups:
comp.lang.c++.moderated
Date:
Thu, 14 Mar 2013 07:17:26 -0700 (PDT)
Message-ID:
<480c071d-2fc9-492c-89b9-a4b629fe04c5@googlegroups.com>
On Thursday, 14 March 2013 13:35:05 UTC+2, DeMarcus wrote:

On 2013-03-13 17:35, ?? Tiib wrote:

On Wednesday, 13 March 2013 00:50:06 UTC+2, DeMarcus wrote:
If it is dynamic polymorphism or dynamic dispatch then get out of
immersion of nullptr. Make a polymorphic smart pointer that instead
of nullptr uses pointer to static "MissingEntertainer" object that
*implements* the interface of Entertainer (just does nothing). Such
pointer can then never be nullptr, can be always dereferenced etc.
I'd call it as robust_pointer. :-)


I agree your solution is better, but you can still accidently provide
nullptr, right?


Because of new loose semantics of list-initializes I currently seem to
make all constructors besides default, copy and move 'explicit'.

With smart pointers I additionally tend to have factory functions
and prefer those when creating the pointers:

   template<class T, class None, /*variadic template parameters*/>
   robust_ptr<T,None> make_robust(/*variadic function parameters*/)
   {/*usual stuff*/ return ret; }

   typedef EntertainerPtr robust_ptr<Entertainer, MissingEntertainer>;

That makes it quite hard that nullptr sneaks in from somewhere
silently and if it comes explicitly from front doors then it will be
converted into MissingEntertainer*.

So I'm still wondering, in order to prevent nullptr to
be used, is it good practice to do this?

void watchShow( std::nullptr_t ) = delete;


But the EntertainerPtr can't never be nullptr.
You will have only that:

   void watchShow( Entertainer& );

Usage is like that:

    Audience a;
    EntertainerPtr p; //default constructs to MissingEntertainer*
    a.watchShow( *p );

Works like charm.

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